A governor is a device for regulating the speed of a prime mover while it is subject to loading. The governor keeps the prime mover speed at or near the desired revolutions per minute by varying the flow of energy to or from it. The governor allows the speed of the prime mover to remain essentially constant regardless of load and other disturbances, or causes the prime mover's speed to change in accordance with operating conditions like the speed setting. When the prime mover drives a generator supplying electrical power at a given frequency, a governor must be used to hold the prime mover at a speed that will yield this frequency. The desired speed is theoretically maintained by the governor regardless of the load or other disturbances.
However, one difficulty with conventional governor systems is that they are often unable to maintain the desired engine speed when the engine is subjected to relatively high loads. Beyond a certain point, the output falls gradually as the load is increased. This phenomenon occurs due to mechanical losses and other limitations of the engine. Thus, at high loads the engine speed drops off to a point lower than the desired speed, which is referred to as the "governor droop."
Another difficulty with governed engines and generators is that when a load is rapidly applied or removed, the system goes into resonance or "ringing" and begins to hunt. When engine hunting occurs, the engine runs faster or slower than the desired speed in an attempt to match the load on the engine instead of running at a steady or constant speed. In an attempt to reach the proper setting, the governor pushes backward and forward quickly, but tends to overshoot the desired speed setting. When hunting occurs in an engine, the effect is annoying and disconcerting to the user. When hunting occurs in a generator, the frequency and voltage of the output varies, for example, causing the lights to dim and brighten. In addition, hunting can cause damage to sensitive electronic equipment. For these reasons, it is desirable for the power output of the engine and generator to remain constant.
Another concern for general applications, e.g., garden tractors, is that the engine idle (no load) speed must be set higher than the required high load speed due to the conventional governor's droop characteristic at high loads. This high idle speed results in obtrusive noise levels and unnecessary engine wear.
The present invention solves these and many other problems associated with currently available governor systems.